Terminals and improved handle for circuit breakers



April 26, 1966 R. B. HEILMAN 3,248,511

TERMINALS AND IMPROVED HANDLE FOR CIRCUIT BREAKERS BY RAYMOND Bl-Iemma HIS QTTORNEVJ April 26, 1966 R. B. HEILMAN 3,248,511

TERMINALS AND IMPROVED HANDLE FOR CIRCUIT BREAKERS Original Filed Jan. 18, 1963 4 Sheets-Sheet 2 SUS PENS|ON STRUCTURE. |9

BROKEN Qwnv HERE AND parz-rw oran-TED com :Lam-w INVENTOR. RAYMOND B. HEILMAN /S HTTORIU April 26, 1966 R. B. HEILMAN TERMINALS AND IMPROVED HANDLE FOR CIRCUIT BREAKERS 4 Sheets-Sheet 3 Original Filed Jan. 18, 1965 lOl 6| m n .M E on v m TE Q WH m mBMm MMX April 26, 1966 R. B. HEILMAN 3,243,511

TERMINALS AND IMPROVED HANDLE FOR CIRCUIT BREAKERS Original Filed Jan. 18. 1963 4 Sheets-'Sheet 4 M'O 9 H8 INVENTOR.

BYRAYMOND B. HEILMAN H/ 5 HTTOQNE J United States Patent C) 3,248,511 y rnNALs AND iMPRovEn HANDLE Fon CiRCUiT rsREAKnns Raymond Il. Heilman, Trenton, NJ., assignor to Heinemann Electric Company, Trenton, NJ., a corporation ot New Jersey Original application Jan. 18, 1963, Ser. No. 252,485. Divided and this application Oct. 21, 1965, Ser. No.

s Claims. (ci. 20o- 166) This application is a division of my copending patent application Serial No. 252,485, filed January 18, 1963.

This invention relates to hermetically sealed electric circuit breakers and more particularly to improved terminals and an improved handle for circuit breakers, and it Y 3,248,511 Patented Apr. 26, 1966 coil, but the handle is held in the contacts closed position is an object of this invention to provide such improved structures.

This invention is used in circuit breakers having an hermetically sealed metal case which is insulated from the current carrying portions of the circuit breaker and the circuit breaker is utilized in an ambient whose temperature may vary between extremely low and high values. One reason for this temperature variation is that, during certain conditions, the lead conductors to the circuit breakers may be at very high temperatures. At. such times, while the overall temperature of the circuit breaker tends to increase, the temperature of the terminals particularly tends to increase, resulting in the tendency of the terminals to expand and contract, relative to the case,

as the temperature of the terminals changes. It is a feature of this invention to secure the terminals relative to the case so that provision will be made for the eX- pansion and contraction of the terminals relative to the case, as the temperature of the terminals increases and decreases, without destroying the hermetic seal Iat the terminals nor impairing the electrical separation between the case and the terminals.

In one embodiment of the invention, two terminals are constructed generally similar to each other except that one is connected by a conductor to the electromagnet of the circuit breaker and the other forms the stationary contact which cooperates with a movable contact, the latter being actuated by a linkage mechanism controlled by a handle (for manual operation) and by an electromagnet (for automatic tripping operation upon predetermined overloads).

Each of the two terminals comprises a central stud section of high strength and corrosion resistance secured to and surrounded along part of its length by a tubular sleeve of a material which has a high electrical conductive property, resulting in electrical shunting of the central stud. In one ofthe terminals, the tubular sleeve forms the stationary contact at one end, while in the other terminal, a conductor is connected between the electromagnet and the ltubular sleeve.

In each terminal there is an insulator bushing connected to the metal case of the circuit breaker and encircling the tubular shunting sleeve and the central stud (for part of their lengths). The tubular sleeve and stud extend through the bushing and are movable relative to the bushing, upon thermal expansion and contraction, due to a flexible annular collar secured at its outer peripheral edge to the bushing and at its inner peripheral edge to the tubular sleeve.

Also, a handley bellows is provided to form a hermetic seal about the handle link so that with the terminals brazed to the metal case and the metal case parts brazed to each other, a completely hermetically sealed unit results.

The foregoing and other objects of the invention, the principles of the invention, and the best mode in which omitting a part of thecounterweight suspension structure for clarity;

FIG. 3 is a view taken along the line 3 3 in FIG. 2 but illustrating the part of the suspension structure omitted in FIG. 2;

FIG. 4 is an enlarged sectional view of the lower portion of the circuit breaker illustrated in FIG. l, but the insulation shown in FIG. 1 surrounding the magnetic blowout and the uper part of the left terminal is omitted in FIG. 4;

FIG. 5 is a top view taken along the line 5 5 in FIG. 4;

FIG. 6 is an exploded view of one terminal, the magnetic blowout piece and the latters support;

FIG. 7 is an. enlarged sectional view of the handle portion;

FIG. 8 is a partial sectional view taken along the line 3 8 in FIG. 7 but omitting certain parts; and

FIG. 9 is a section view taken along the line 9 9 in FIG. 8.

Referring to the drawings, a circuit breaker 10 is illustrated having a metallic case 11, preferably of stainless steel and partly broken away in FIG. 1 to expose certain internal structure, through which extend terminals 12 and 13. The terminal 13 includes a stationary contact 15 at its upper end which cooperates with a movable contact 17 carried by a movable arm 1S. The movable arm 18 is actuated by a linkage mechanism 20 controlled by an electromagnetic device 16, a counterweight suspension structure 19 being associated with the latter, all of which are described in detail and claimed in applications led by Raymond B. Heilman and Harold H. Bahr on December 24, 1962, Serial No. 246,699; by Raymond B. Heilman on January 18, 1963, Serial No. 252,404; and by Ronald Nicol on January 18, 1963, Serial No. 252,413, now Patent No. 3,221,122; and consequently they are, not described in detail herein. Manual opening and closing of the contacts 15 and 17 is etfectuated by a handle 21, whereas electromagnetic tripping lof the contacts to the open position is controlled by the downward movement of the tube 26.

The linkage mechanism 20 comprises two groups of links referred to for convenience as the handle toggle or lirst group 23 and the main toggle or second group 24. Briey, pivotal counterclockwise movement of the handle 21, starting from the open contacts position of FIG. 1, causes the handle toggle links 23 comprising the handle link 27 and a link of varying length 28 (joined together by a knee pintle 30) to move to the right and the handle force to be transmitted by a coupling link 32, from the link of varying length 28 to the knee pintle 33 of the main toggle links 24, the latter comprising the toggle links 36 and 37 and the catch link 39. The lower toggle link 37 is, in turn, connected to the movable contact arm 18, whereby movement ofthe handle 21 results in the movable arm 18 being rotated in the counterclockwise direction, closing the contacts 15 and 17. In the closed position of the contacts, the catch link 39 is restrained from movement by a lock 45 carried by a cradle 46. In turn, the cradle 46 is restrained by the lock 52 (the latter shown in FIG. 3 after release of the cradle 46) from moving in the counterclockwise direction (due to the bias imposed on the cradle 46 by the catch link 39) from the force of the opening springs 47.

When the tube 26 moves downwardly a sufcient distance, upon predetermined overloads, the tube 26 pivots clockwise (FIGS. 1 and 3) the suspension structure 19 suiciently to engage the lock 52 and rotate the latter in the clockwise direction also. Sul'icient clockwise rotation of the lock 52 results in the release of the cradle 46 from the lock 52, whereby the catch link 39 is released from its lock 45 and the upper end of the catch link 39 moves in the clockwise direction under the bias of the opening springs 47. This clockwise movement of the catch link 39 causes the main toggle (formed by links 36 and 37) to collapse due to the pressure of the opening springs 47, whereupon the contacts open. During the collapse of the main toggle links, the knee pintle 33 of the handle toggle is moved overcenter y(toward the left) suiciently for the spring 56 (carried by the link of varying length 28) to help reset the mechanism.

The bottom and initially separate part 60 of the metal case 11 is provided with two circular Iholes 61 and 62 defined by two annular U-flanges 63 and 64, respectively, the free end rims 65 being inturned, into the case interior. Peripherally furnace brazed in a vacuum only to the inner annular surfaces 66 (and not brazed to the bases 66a of the U-shapes nor the outer annular surfaces 66b) are ceramic bushings 67 and 68, each of the latter extending through and into the case (in abutment with the bases 66a) and yhaving a portion depending from the case, the bushings 67 and 68 being preferably formed from a high alumina ceramic.

Extending through axial holes 69 and 70, in each of the ceramic bushings 67 and 68, but annularly spaced from the cylindrical bushing walls defining the holes 69 and 70, so as to define annular spaces 57 and 58, are electrical conductors or shunt sleeves 71 and 72 secured to electrical conductors or studs 73 and 74, respectively, of high mechanical strength relative to t-he `shunt sleeves but of lower electrical conductivity relative `to the latter.

The sleeves 71 and 72 are secured to their respective bushings -67 or 68 by annular thin and flexible (relative to the other parts of the terminals) collars or washers 77 and 78, each of the latter being brazed at its outer circular peripheral portion to the associated bushing 67 or 68 (at the lower part thereof on the outside of the case 11) and brazed adjacent its inner circular peripheral portion to the outer surface of the associated sleeve 71 or 72.

As illustrated in FIG. 4, the collars 77 and 78 have a general U-shape in cross-section, and the shunt sleeves 71 and 72 each have an enlarged lower portion. The collars 77 and 78 are placed around the shunt sleeves 71 and 72 with the inner surface of the collars 77 and 78 partly in abutment with the enlarged lower ends of the sleeves `71 and 72 and peripherally brazed to the outer surface of the shunt sleeves 71 and 72 just above their enlarged ends, a shoulder at the juncture of the enlarged ends with the remainder of the sleeves being used to receivc rings 93 of the brazing material used during the brazing. .The collars 77 and 78 are brazed at their peripheral outer portions to the lower enlarged portions of the bushings 67 and 68, brazing rings 94 being interposed between the two. The thickness of each collar is such that only a radial part of each of the spaces 69 and 70 is occupied by the peripheral portions that are brazed to the sleeves 71 and 72 and the collars do not extend very far into the spaces 69 and 70, as illustrated. Also, inclined spaces 57a and 58a are formed, in communication with the spaces 57 and 58, the spaces 57a and 58a being between the portions of the collars which are brazed to the bushing y67 or 68 and the portions which are brazed to the sleeve 71 or 72. As illustrated, the enlarged lower portions of the bushings 67 and 68 are disposed below l the flanges 63 and 64 and radially outward of the annular surfaces 66 of the flanges 63 and `64.

It is seen from the foregoing that axial and radial expansion and contraction of the studs 73 and 74 and of the sleeves 71 and 72 is accommodated by the axial and radial flexibility of the collars 77 and 78.

The shunt sleeves 71 and 72 are preferably formed from a silver-magnesium-nickel alloy and are mechanically secured to the studs 73 and 74 -by -having three spaced, circumferential portions 82 thereof crimped (FIG. 6) into annular grooves 34 formed in the studs and circumferentially brazed thereto at the groove 84 also. The studs 73 and 74 are preferably formed from stainless steel and are threaded below the shunt sleeves 71 and 72, as illustrated, to receive external lead conductors (not illustrated) which are suitably biased by threaded connectors 79 and 80 (FIG. l) against annular depending beads 86 (at the lower end of the sleeves 71 and 72) to insure proper physical contact and electrical conduction, the beads 86 bring below the lowest parts of the collars 77 and 78.

As illustrated in FIG. l, an electrical conductor 90 is connected at one end to the sleeve 72 and to the coil of the electromagnet 16 at the other end. The coil is in turn connected to the movable arm 18 by a exible conductor 921. The stationary contact 15 is integral with and formed by the upper closed end of the sleeve 71 so that when the contacts are in abutment, the electrical circuit is completed.

The circuit breaker, as illustrated, is provided with a U-shaped magnetiza'ble member 96, preferably made of iron, -having legs 97.connected by a bight 98 and further described and claimed in Raymond B. Heilman Patent No. 3,016,438. However, unlike the arrangement disclosed in the mentioned patent, in this invention, the magnetizab'le member 96 is properly positioned by a support 99 comprising a yoke 1011 `and a finger 102 of electrically conductive material but nonmagnetic, such as stainless steel, the yoke 101 frictionally and tightly clasping a icirctun-ferential part of the sleeve 71, as illustrated, and the finger 102 being brazed to the inside of the bight 98, between the Ilegs 97.

Initially, the terminals 12 and 13 are `assembled as separate similar units, since the terminal y13 is substantially the same as the terminal .12 prior to addition of the blowout member 96 and the embedding insulation material 106. The terminals 12 and 13 are then placed in proper position extending through the -holes 611 and 62, with the enlarged ends of the bushings abutting the base of the U-shaped rims and the bushings are then brazed to the annular surfaces 66.

The rnagnetizable blowout member 96 is then added to the terminal 13 and the support 99 positioned so that the bottom surface of the rnagnetizable member 97 is above the surface of t-he contact 15. Thereafter, an electrical insulation material 106, FIG. 1, preferably a owable silicone rubber compound, is painted on the magnetizable 'member 96 and the finger 99. Some of the insulation material is also placed in the cavity formed by the curved surface 104 of the bushing 67 and the yoke 101 and overlies an annular shoulder formedV by the end of the shunt sleeve 71 below the contact y15, as illustrated in FIG. 1.

The insulation 106 has elastic qualities permitting relative movement between the shunt sleeve 71 and the bushing 67 without cracking the ceramic bushing or destroying the hermetic sea-l. The 'silicone rubber insulation 106 vulcanizes at room temperature and takes the shape illustrated in IFIG. 1 although some does extend down into the annular space 57 between the sleeve 71 and bushing 67.

As partially illustrated in =FIG. 1, `silicone rubber insulation 106 is also applied to the upper end of the sleeve 72 (of terminal 12) to embed the connection between as follows.

the conductor 90 and the sleeve 72, as well as lling the space 70.

From the foregoing it is seen that the insulation material 1616 about the magnetizable member 96 and the support 99 therefor embed the last two mentioned elements but the insulation 106` has no elect on the malgnetic lines of :flux which are induced by the current in the magnetizable member 96 and the arc controlling function of the latter. However, if an arc should form, the insulation l1416 will prevent the arc rfrom striking the magnetic blowout member 96.

Thus, as the terminal 13' expands and contracts longitudinally with temperature changes, the support 99 carries with the sleeve 71 the magnetizable member 96 at all times in proper relation with the surface f contact 15.

Further, as the unit is subjected to changes in temperature, the positions of the terminals l12 and l13 relative to the case part 60 change ydue to the flexibility -in the flanges `613 and 65. More importantly, as the temperature changes, the sleeves and studs will expand and contr-act. Since the sleeves are spaced [from the bushings by the annular spaces, and the collar is relatively thin and of U-shape, as illustrated, changes in the sleeves and studs Iare accommodated by the collars. The magnetic blowout member 96 remains in its correct position during such changes and is embedded in insulation so that any arc that may tend to form on contact separation will `be interrupted should it attempt to jump onto the blowout member.

After applying the rubber compound to the upper ends of the terminals 12 and |13 and allowing it to set sufficiently, assembly of the -circuit breaker may be continued For this purpose, as illustrated in FIG, 4, there is secured to the left band portion of the peripheral flange off the lower case part l60 an upstanding U-s-haped (FIG. assembly plate 110. Intermediate the legs of the assembly plate I110 are placed the two spaced and opposed frame plates 120, FIG. 2, :between whichl is mounted the linkage mechanism 20, some of the linkage pintles extending through to engage the legs of the assembly plate 110, whereby the linkage lmechanism is positioned relative to the lower case part 60.

The linkage mechanism 20, aspositioned on the lower case part i60, is then inserted into the main case part 112, with the handle link 27 extending partly through a hole A121 in the main case part 1.112, as illustrated in FIGS. 1 and 7, until the `frame grooves or notches 1117 of the `frame plates 120 (FIG. 1) are seated against the locating insulator 118, the latter being carried by a handle bracket 124i, and when so received the linkage is correctly positioned within the case part 112.

As illustrated in FIGS. l and 7, the hole 121 through which the handle link 27 extends is ydeined by a circular collar 1212 yformed in the case part v112, a dished member 114i being seated on the collar 12-2. The handle bracket 124 is formed by two symmetrical halves each of which comprises two plates 108 and 109 welded to each other, the plate 109 having bent ends y123i, FIG. 9, the ends 123 being turned 90 lfrom the main portion of the plate 109 and welded to an inside surface portion of the case part 112. The plate l109 has a central portion which extends through the hole 1211, as illustrated in FIGS. l, 7 and 9, Iand the plate 1141-8 has an abutting similar central 4portion and these central portions jointly define a holder 126 for carrying a pintle 125 extending through the handle link 27 and about which the latter is movable.

Also, the plate 109 has la lower portion 140 turned outwardly to support the lside plates 1.35 carrying the insulator 118. The handle bracket .412-4 also carries fixed stops 127 and 128 for limiting arcuate travel of the handle link 27, the support plates |135 -for the insulator 118 being also connected to the ends of the stops 127 and 128.

The hermetic seal at the handle link 27 is provided by a one piece, elongated metallic bellows 113, which is generally cylindrical in shape, having its lower, open end peripherally brazed to the ilange of the circular dished member 114 and its closed, upper end extending over (and about) the upper end of the handle link 27, above the pintle 125, as illustrated in FIG. 7, the bellows 113 being formed preferably from nickel. The dished member 114 which is seated on the collar 1 22 defining the circular hole 121 has a radially inwardly extending ilange to which the bellows 113 is brazed, the ilange being disposed within the confines of the case part 112.

The upper end of the handle link 27 is provided with a shoulder against which is seated a circular washer 130 which supports a part of the bellows 113 in the transition from the larger diameter thereof to the smaller diameter about the upper part of the handle link 27.

Between the washer 130 and the upper end of the handle link 27 and between the portion of the handle 21 interlitting with the handle link 27 is a cylindrical sleeve 132. Also, between the washer 130 and the upper end of the handle link 27, the handle link is provided with a groove 133.

Thus, after the linkage has been assembled within the case and the handle link 27 extends through the hole 121 and with the washer 130 and sleeve 132 in position, the bellows 113 and the dished member 114 (which have been previously brazed together) are slipped over the handle link 27 and the dished member is pressed into position over the collar 122, an interference tit being provided between the latter two. The circular juncture between the dished member 114 and the collar 122 is hermetically sealed with a silicon rubber compound which vulcanizes at room temperature. It should be understood, however, that this juncture could be sealed by brazing if desired.

The handle 21 is then placed over the upper end of the bellows 113, a dished guard member having been previously secured to the lower end of the handle 21, and when in proper position (slightly spaced from the portion Iof the bellows 113 lying upon the Washer 131i), a pe- `ripheral portion of the handle 21 is crimped inwardly into the groove 133, deforming the associated portions of the bellows 113 and sleeve 132, the sleeve protecting the bellows portion at such time against rupture, particularly by the corners defining the groove.

Hermetic sealing of the circuit breaker is completed by brazing to each other the lower and main case parts 6@ and 112.

Thus, it is seen that an improved hermetically sealed circuit breaker has been provided by the terminals and handle structures described and th'e brazing of the stainless steel casing parts to each other.

Having described this invention, I claim:

1. A terminal structure for a circuit breaker having a metal case comprising a ceramic bushing brazed to the case for the circuit breaker, said bushing including a wall dening a hole, an electrical conductor extending through said hole in spaced relation to the wall of said bushing defining sa'id hole and insulated from the metal case by said bushing, said electrical conductor comprising an axial stud and a shunt sleeve, said shunt sleeve being formed from a material which is a better electrical conductor than the material from which said stud is formed, said shunt sleeve having an end portion outside of the metal case adapted to be engaged by an external conductor to be secured to the terminal structure, said stud having a threaded portion associated with said sleeve end portion to receive a fastening means whereby the external conductor may be fastened against said shunt sleeve end portion, said stud being formed from a material which has a higher strength than the material from which said shunt sleeve is formed, said shunt sleeve including a wall delining a hole receiving a portion of said stud in intimate contact with said shunt sleeve wall, and a flexible collar of annular shape having an inner peripheral portion brazed to said shunt sleeve and an outer peripheral portion brazed to said ceramic bushing, and said collar being disposed outside of the metal case, whereby expansion and contraction of said sleeve and stud relative to said ceramic bushing is accommodated by said collar.

2. The structure recited in claim 1 and further including a magnetizable member to control the are that tends to form upon the separation of the circuit breaker contacts, said shunt sleeve having a closed end disposed inside the circuit breaker case and forming the stationary contact of the circuit breaker, a metal support connected to said magnetizable member and to said shunt sleeve for positioning said magnetizable member in correct relationship to said stationary contact.

3. The structure recited in claim 2 and further including an electrical insulation material embedding said magnetizable member and a part of said support, thereby electrically insulating said magnetizable member.

4. The structure recited in claim 3 and further including an annular U-shaped flange formed in part by the circuit breaker case, said ceramic bushing being brazed to the inner leg of said U-shaped flange only.

5. A terminal structure for a circuit breaker having an overload sensing device and a metal case comprising an insulator secured to the case of the circuit breaker, a cylindrical shunt conductor sleeve secured to and extending through said insulator, into said case and being electrically connected inside said case to said overload sensing device, and a cylindrical stud secured to said cylindrical shunt conductor sleeve, said cylindrical stud having means to receive and securely hold an external conductor in electrical conducting relationship with said cylindrical shunt conductor sleeve, said cylindrical shunt conductor sleeve being formed from a material of high electrical conductivity relative to said cylindrical stud, said cylindrical stud being formed from a material of high mechanical strength relative to said cylindrical shunt conductor sleeve, said cylindrical shunt conductor sleeve having an end portion within said case and an opposite end portion outside of said case with which said external conductor'is connectable in electrical conducting relationship, the end portion Aoutside of said case receiving a part of said cylindrical stud, said cylindrical shunt conductor sleeve being mechanically and electrically secured to said stud.

l6. A terminal structure for a circuit breaker having an overload sensing device and a metal case comprising an insulator secured to the case of the circuit breaker, a shunt conductor sleeve secured to and extending through said insulator, into said case and being electrically connected inside said case to said overload sensing device, a stud secured to said shunt conductor sleeve, said stud having means to receive and securely hold an external conductor in electrical conducting relationship with said shunt conductor sleeve, said shunt conductor sleeve being formed from a material of high electrical conductivity relative to said stud, said stud being formed from a material of high mechanical strength relative to said shunt conductor sleeve, and flexible means connected to said insulator and to said shunt conductor sleeve to mount said shunt conductor sleeve and said stud to said insulator to permit movement of said shunt conductor sleeve and said stud relative to said insulator.

7. A hermetically sealed electromagnetic circuit breaker comprising a metal case enclosing a linkage, a handle link extending outside of said case at one end portion and connectedv to said linkage at the other end portion, a flexible bellows having a closed end for enclosing said end of the handle link extending outside said case, said bellows -being brazed at its open end to said case in communication with the interior thereof, terminals secured to said case, said terminals including an electrical conductor and a ceramic insulator electrically insulating said conductor from said case, said terminals including a flexible connection between said conductor and said ceramic insulator, said case being formed from a plurality of parts brazed to each other whereby the brazed casing parts, brazed bellows to case and brazed terminals to case, result 1n an hermetically sealed circuit breaker, said case having wall structure dening a hole through which said handle link extends, a bellows disposed over the handle link portion extending outside said case, said bellows having an open end portion hermetically sealed to said wall structure, said bellows being closed at its opposite end portion, a bracket secured to said case and extending through said hole, a pintle carried by said bracket and on which said handle link is pivotally mounted, said bellows including convolutions about said pintle which extend axially above and below said pintle, a handle attached to said handle link outwardly of said pintle, said handle securing said handle link and said bellows closed end portion to each other for joint actuation.

3. A handle hermetic sealing arrangement for circuit breakers comprising a metal case enclosing a linkage, a handle link extending through said case, said case having wall structure defining a hole through which said handle link extends, a bellows disposed over the handle link portion extending outside said case, said bellows having an open end portion hermetically sealed to said wall structure, said bellows being closed at its opposite end portion, a bracket secured to said case and extending through said hole, a pintle carried by said bracket and on which said handle link is pivotally mounted, said bellows including convolutions about said pintle which extend axially above and below said pintle, a handle attached to said handle link outwardly of said pintle, said handle securing said handle link and said bellows closed end portion to each other for joint actuation.

References Cited by the Examiner UNITED STATES PATENTS 2,162,477Y 6/1939 Cox 174-152 2,341,920 2/1944 Hull 174-152 X 2,450,780 10/1948 Bucklen 174-152 X 3,014,106 12/1961 Jennings 200-144 3,015,010 l2/l96l Greeson 200-168 X 3,021,408 2/1962 Jennings 20G-144 3,187,299 6/1965 Marta 339-278 X 3,206,562 9/1965 Griggs et al ZOO-144 X ROBERT K. SCHAEFER, Primary Examiner.

H. O. JONES, Assistant Examiner. 

5. A TERMINAL STRUCTURE FOR A CIRCUIT BREAKER HAVING AN OVERLOAD SENSING DEVICED AND A METAL CASE COMPRISING AN INSULATOR SECURED TO THE CASE OF THE CIRCUIT BREAKER, A CYLINDRICAL SHUNT CONDUCTOR SLEEVE SECURED TO AND EXTENDING THROUGH SAID INSULATOR, INTO SAID CASE AND BEING ELECTRICALLY CONNECTED INSIDE SAID CASE TO SAID OVERLOAD SENSING DEVICE AND A CYLINDRICAL STUD SECURED TO SAID CYLINDRICAL SHUNT CONDUCTOR SLEEVE, SAID CYLINDIRCAL STUD HAVING MEANS TO RECEIVE AND SECURELY HOLD AN EXTERNAL CONDUCTOR IN ELECTRICAL CONDUCTING RELATIONSHIP WITH SAID CYLINDRICAL SHUNT CONDUCTOR SLEEVE, SAID CYLINDRICAL SHUNT CONDUCTOR SLEEVE BEING FORMED FOM A MATERIAL OF HIGH ELECTRICAL CONDUCTIVITY RELATIVE TO SAID CYLINDRICAL STUD, SAID CYLINDRICAL STUD BEING FORMED FROM A MATERIAL OF HIGH MECHANICAL STRENGTH RELATIVE TO SAID CYLINDRICAL SHUNT CONDUCTOR SLEEVE, SAID CYLINDRICAL SHUNT CONDUCTOR SLEEVE HAVING AN END PORTION WITHIN SAID CASE AND AN OPPOSITE END PORTION OUTSIDE OF SAID CASE WITH WHICH SAID EXTERNAL CONDUCTOR IS CONNECTABLE IN ELECTRICAL CONDUCTING RELATIONSHIP, THE END PORTION OUTSIDE OF SAID CASE RECEIVING PART OF SAID CYLINDRICAL STUD, SAID CLYINDRICAL SHUNT CONDUCTOR SLEEVE BEING MECHANICALLY AND ELECTRICALLY SECURED TO SAID STUD. 